Noise Reduction Stethoscope for United States Navy Application

Abstract

conducted in compliance with all applicable federal regulations governing the protection of human subjects in research.The authors wish to acknowledge Derek Schwaller, our biomedical engineer, for his tireless, conscientious achievements in instrumentation, data gathering, digital editing and signal analysis. Special acknowledgment is due to Surgeon Commander Steven Ryder, Royal Navy for invaluable guidance during the design of this research and clinical evaluation of our selected "patients". We greatly appreciate the voluntary efforts of LT Michael Waltz, MC, who took over as medical monitor for LT Jackman MC, and who, was not only able to enlist our highly trained medical listeners on short notice, but also endured at least five hours as a subject himself. We appreciate the efforts of all our participants for their conscientious performance, patience and endurance in such a demanding task. We are intensely grateful to Lynne Marshall for her extensive editorial efforts as a reviewer to help make this report more clearly convey our findings.This research is dedicated to Thomas E. Hanna, a Braveheart who led by example. Thanks for your confidence and support from the onset.Joseph S Russotti, is Principal Investigator, and Thomas P. Santoro, LT Robert Jackman, MC, LT Deborah White, MSC, are all Associate Investigators on this project at the Naval Submarine Medical Research Laboratory. The co-authors are listed in alphabetical order since each contributed equally to this research project.ii SUMMARY PAGEThe Problem: Conventional stethoscopes cannot function effectively unless ambient noise is maintained at approximate examination-room levels. This serious limitation inhibits diagnosis and monitoring of patients in a variety of common military medical situations: in field hospitals, in high ambient noise environments such as engine rooms, in vehicles such as ambulances, fixed and rotary wing aircraft, or in hyperbaric chamber treatment facilities. Trying to measure blood pressure, determining if a faint heart-beat is present in a casualty, or listening to respiratory events can be nearly impossible under field conditions.The Approach: The objective of this project was to evaluate commercial off-the-shelf (COTS) products and recommend one or several compact noise-reducing/canceling stethoscopes for field, medical-transport, and shipboard use, in moderately noisy environments (up to 90 dB SPL). At the onset of this project a working group was convened to assess Navy need and requirements for a noise-reducing stethoscope for casualty care and general medical use. In general terms, given present and projected COTS state-of-the-art technology, a modular approach using a simpler device tailored to the application, will be more cost-effective, for general-issue, than a single device. We selected three such simpler devices for laboratory testing using both the listening-headsets provided, and a highly accurate active noise cancellation (ANC) headset.The Findings: Laboratory data show exceptional performance of noise reducti...